Make chat composer scrollable with height constraints

- Changed wrapper from fixed h-7 to min-h-7 with max-h-32 (up to 128px)
- Added overflow-y-auto to allow vertical scrolling when content exceeds height
- Changed items-center to items-start for proper content flow from top
- Added width: 100% to ProseMirror to ensure full-width rendering
- Added word-wrap and overflow-wrap to ProseMirror paragraphs for proper text wrapping

Now users can type multi-line messages (Shift+Enter) and the composer will
scroll vertically while maintaining a reasonable maximum height.

src/components/editor/MentionEditor.tsx

@@ -875,12 +875,9 @@ export const MentionEditor = forwardRef<
 
     return (
       <div
-        className={`rounded border bg-background transition-colors focus-within:border-primary h-7 flex items-center overflow-hidden ${className}`}
+        className={`rounded border bg-background transition-colors focus-within:border-primary min-h-7 max-h-32 flex items-start overflow-y-auto overflow-x-hidden ${className}`}
       >
-        <EditorContent
-          editor={editor}
-          className="flex-1 min-w-0 overflow-x-auto"
-        />
+        <EditorContent editor={editor} className="flex-1 min-w-0" />
       </div>
     );
   },

src/index.css

@@ -283,6 +283,7 @@ body.animating-layout
 .ProseMirror {
   min-height: 1.25rem;
   line-height: 1.25rem;
+  width: 100%;
 }
 
 .ProseMirror:focus {
@@ -292,6 +293,8 @@ body.animating-layout
 .ProseMirror p {
   margin: 0;
   line-height: 1.25rem;
+  word-wrap: break-word;
+  overflow-wrap: break-word;
 }
 
 .ProseMirror p.is-editor-empty:first-child::before {